It has been a challenge in the research field of virtual reality how to make a subject perceive an incident that is not actually happening in front of him (for example, an incident displayed in an artificial content, an incident displayed in a past video image, or an incident at a location other than the viewing site) as an incident actually happening in front him.
For example, “augmented reality” and “telepresence” are among the above techniques.
In the “augmented reality,” a live video image from the user's viewpoint is displayed on a display (for example, a head-mounted display worn by the subject on the head) with a CG technology video image superimposed thereon (for example, see Patent Literature 1 to 3 below).
On the other hand, in the “telepresence,” a video image captured by a remotely-located camera is displayed in real time on a head-mounted display worn by the viewer on the head and the imaging orientation of the camera is remotely controlled in conjunction with the movement of the head of the viewer.
For example, Patent Literature 1 below discloses a technique of capturing an image in the orientation behind a portable display with a camera and superimposing on the image an image of a three-dimensional virtual object in accordance with the position and orientation of the camera. This technique is considered to enable the user to experience a feeling of the three-dimensional virtual object actually existing.
Furthermore, Patent Literature 2 below discloses a technique of capturing with a camera an image of an object on which a two-dimensional code is printed, acquiring information corresponding to the two-dimensional code from a database, and displaying the acquired information and object in a superimposed manner on a display.
Furthermore, Patent Literature 3 discloses a technique of identifying the image data matching captured image data captured by imaging means and acquiring a web site corresponding to the image data from the WWW server.